Advances in soft robotics, materials science, and stretchable electronics have enabled rapid progress in soft grippers. Here, a critical overview of soft robotic grippers is presented, covering different material sets, physical principles, and device architectures. Soft gripping can be categorized into three technologies, enabling grasping by: a) actuation, b) controlled stiffness, and c) controlled adhesion. A comprehensive review of each type is presented. Compared to rigid grippers, end-effectors fabricated from flexible and soft components can often grasp or manipulate a larger variety of objects. Such grippers are an example of morphological computation, where control complexity is greatly reduced by material softness and mechanical compliance. Advanced materials and soft components, in particular silicone elastomers, shape memory materials, and active polymers and gels, are increasingly investigated for the design of lighter, simpler, and more universal grippers, using the inherent functionality of the materials. Embedding stretchable distributed sensors in or on soft grippers greatly enhances the ways in which the grippers interact with objects. Challenges for soft grippers include miniaturization, robustness, speed, integration of sensing, and control. Improved materials, processing methods, and sensing play an important role in future research.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201707035

Soft Robotic Grippers.

This work presents a novel technique for direct 3D printing of soft pneumatic actuators using 3D printers based on fused deposition modeling (FDM) technology. Existing fabrication techniques for soft pneumatic actuators with complex inner geometry are normally time-consuming and involve multistep processes. A low-cost open-source consumer 3D printer and a commercially available printing material were identified for printing soft pneumatic actuators with complex inner geometry and high degree of freedom. We investigated the material properties of the printing material, simulated the mechanical behavior of the printed actuators, characterized the performances of the actuators in terms of their bending capability, output forces, as well as durability, and demonstrated the potential soft robotic applications of the 3D printed actuators. Using the 3D printed actuators, we developed a soft gripper that was able to grasp and lift heavy objects with high pay–-to-weight ratio, which demonstrated that the ...

High-Force Soft Printable Pneumatics for Soft Robotic Applications

With the rise of soft robotics technology and applications, there have been increasing interests in the development of controllers appropriate for their particular design. Being fundamentally different from traditional rigid robots, there is still not a unified framework for the design, analysis, and control of these high-dimensional robots. This review article attempts to provide an insight into various controllers developed for continuum/soft robots as a guideline for future applications in the soft robotics field. A comprehensive assessment of various control strategies and an insight into the future areas of research in this field are presented.

Control Strategies for Soft Robotic Manipulators: A Survey.

Soft robotics is a growing area of research which utilises the compliance and adaptability of soft structures to develop highly adaptive robotics for soft interactions. One area in which soft robotics has the ability to make significant impact is in the development of soft grippers and manipulators. With an increased requirement for automation, robotics systems are required to perform task in unstructured and not well defined environments; conditions which conventional rigid robotics are not best suited. This requires a paradigm shift in the methods and materials used to develop robots such that they can adapt to and work safely in human environments. One solution to this is soft robotics, which enables soft interactions with the surroundings whilst maintaining the ability to apply significant force. This review paper assess the current materials and methods, actuation methods and sensors which are used in the development of soft manipulators. The achievements and shortcomings of recent technology in these key areas are evaluated, and this paper concludes with a discussion on the potential impacts of soft manipulators on industry and society.

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Soft manipulators and grippers: A review

This article presents the design principle and fabrication of a variable stiffness soft robotic gripper for adaptive grasping and robust holding. The proposed robotic gripper is based on a finger design that combines a fiber-reinforced soft actuator and a particle pack. The soft actuator is responsible for the bending motion of the finger, and the particle pack acts as a stiffness-changeable interface between the finger and the object. In the natural state, the particle pack is soft and adaptive to part geometry. It can rapidly stiffen (through vacuum) to resist external load or to freeze the currently bent contour of the finger. Experimental studies have shown that more than a 10-fold stiffness enhancement is achievable. Therefore, the proposed gripper is capable of handling objects with different shapes, weights, and rigidities, which have been a great challenge for robotic grasping. For more effective grasping, a grasping strategy is designed for the proposed soft gripper with simultaneous con...

A Novel, Variable Stiffness Robotic Gripper Based on Integrated Soft Actuating and Particle Jamming

The present article shows the development of a gripper for general purposes with grasping and holding capabilities enabled by a simple control scheme. This objective has been reached exploiting the combination of soft materials, underactuated mechanisms, and a bioinspired design. The development of the soft gripper will be explained by reporting the results obtained on three different and sequential versions. The devices are here presented in their main components, underlining the anthropomorphic approach used in the design of the fingers. The used actuation mechanism is based on the control of a single cable tension, which guarantees a grasping adaptable to objects of different shape. Manipulation capability and grasping force have been tested, in order to extract a quantitative comparative analysis between the three proposed devices. The main factor that influences the improvement of the gripper performance results to be represented by the suitable combination of material with the right mechani...

A Bioinspired Soft Robotic Gripper for Adaptable and Effective Grasping

This article introduces a machine-learning-based approach for closed loop kinematic control of continuum manipulators in the task space For this purpose, we propose a unique formulation for learning the inverse kinematics of a continuum manipulator while integrating end-effector feedback We demonstrate that this model-free approach for kinematic control is very well suited for nonlinear stochastic continuum robots The article addresses problems that are vital for practical realization of machine-learning techniques The primary objective is to solve the redundancy problem while making the algorithm scalable, fast, and tolerant to stochasticity, requiring minimal sensor elements and involving few open parameters for tuning In addition, we demonstrate that the proposed controller can exhibit adaptive behavior in the presence of external forces and in an unstructured environment with the help of the morphological properties of the manipulator Experimental validation of the proposed controller i

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Papers

A Bioinspired Soft Robotic Gripper for Adaptable and Effective Grasping

Learning Closed Loop Kinematic Controllers for Continuum Manipulators in Unstructured Environments